Due to the increased popularity of free fall sky diving throughout this nation, and the world, and the demand for a safer, more controlled velocity air flow simulator to provide a base for the introduction of the free fall sensation and human flying aspects to the general public, and act as a true training simulator to the novice, and, on through the advanced sky diver, wishing to practice their free fall skydiving techniques, the inventor has produced a freefall simulator, which he believes to be a much improved and much safer machine than has been taught by the prior arts. As a result of this invention, several of the prior arts were studied, and, has been the experience of the inventor, all of these arts have some serious deficiency's, or, faults, which make them unacceptable for use as a general public free fall simulator, or, sky diver training device, or, advanced certification simulator.
These deficiency's seem to fall into three major categories:; 1. Safety of the design, 2. Noise pollution, and 3. Non-linear power transmission from the power source to the propeller, through the entire power range of the motor. The inventor has spent many Years working with the results of the prior arts, has noted these deficiency's, and has invented a freefall simulation machine which he feels has either eliminated the above problems, or, has greatly improved the art. The following background information will point out the inherent problems encountered in the prior arts, and explain what the inventor has done to correct them. In the design of this machine. An example of one of these faults is taught in the art of Jean St. Germain, in U.S. Pat. No. 4,457,509, where a freefall simulator is constructed using a reciprocating motor, a gear type transmission, and a drive shaft mechanism equipped with universal joints, or, flexible couplings to drive the propeller. Such arrangements of gear driven propellers to supply the stream of air have several inherent operational and safety problem areas, and, contribute to the noise pollution problems when utilized in a high RPM, high torque, power transmission application. These problems arise due to the excessive costs associated with trying to design around the standard aircraft drive system, which is normally a system of planetary gears, too expensive for these simulator applications. In the prior arts studied, and, from past experience of the inventor, these replacement gear driven drive systems, and transmissions, when under power, cause certain components to experience, or create, frequency harmonics, which when allowed to amplify, cause major vibration problems, resulting in physical damage to the transmission unit, the drive shaft, the universal joints, and in some cases, has caused the transmission to actually explode, causing physical injuries to the user of the free fall simulator, and to some of the spectators, not to mention the damage to the equipment, and structure itself. Also, the use of this type of gear train requires constant inspection and maintenance during use, which creates an unsafe working condition for the maintenance person. Annual rebuilding of these units is common practice. In addition, these gear driven units introduce a tremendous noise pollution problem to the surrounding area. Aside from these inherent safety, and noise problems, the inventor found that it is impossible to match the power output of the drive motor to the power needs of the propeller, to furnish the correct air speed to meet the requirements of the various weights of the users, and, in the past experience of the inventor, none of the prior arts could produce the required air speed to meet the terminal speed requirements of the heavier users, and "balloon suits" were required in order to produce a freeflight situation for these persons. The gear shifting nature of a gear type transmission, whereby the maximum power output of any gear arrangement is centered at some mid-range of the gear match chosen, with a somewhat delayed response decrease as the RPM of the motor is decreased, or increased. The power curve derived from a gear train is definitely not a linear function, with the resultant fact that these prior arts cannot continually produce the required air stream speeds for participants of varying weights. The inventor has overcome these problems by employing a new type of hydraulic drive system for the unit. This drive unit employs a high horsepower electric motor, driving two individual hydraulic pumps, each of which feeds power to a hydraulic motor, which in turn, drives the propeller. One of these hydraulic pumps is of a constant output, and supplies 50% of the power requirements of the driving hydraulic motor. The second of these pumps is of a variable output, and, supplies the remainder of the power requirements of the driving motor on a demand basis. If the user of the freeflight machine is of a light weight, then the second hydraulic pump would be set to furnish a lower output than if the user was of a higher weight, but, in each case, the two pumps working in conjunction, can furnish enough power to the driving motor to create the terminal velocity required by the most demanding user. This power is derived without any shifting, or matching, of gears, etc., and a smooth linear transmission of the power from the powering motor to the propeller is attained, producing the correct amounts of air stream for the weight of the person using the Freefall simulator. This hydraulic drive method is thought by the inventor to be a new and unique adaptation of a hydraulic drive system to the simulator industry.
Another problem of the freefall simulator industry, which has been overcome by the inventor, is the directing of the air stream from the propeller, up through the air stream container, to the user, in a full, even volume and even dispursement of air to all areas of the air stream, with no low velocity streams in the center of the air column. In all of the prior arts, studied by the inventors of this freefall simulator, this problem of the low velocity air stream over the center of the propeller, and, on up the air stream, has been encountered. The inventor of the freefall simulator has corrected this problem. The inventor of the freefall simulator has found that this problem is derived from the circular rotation of the propeller, which allows for the slippage of air from the tip of the propeller, and several other parameters. To correct for this problem, the inventor has installed a three step baffle system. The first step, directly over the propeller, is a set of curved baffles, which re-directs the air stream in a true vertical direction, and eliminates most of the swirls. Directly above these vertical baffles are two sets of "S" shaped baffles, one set which directs some of the air stream towards the center of the air stream, above the hub of the propeller, and the other set further from the center of the air stream, which directs the air stream outward from the center of the propeller, and which enlarges the diameter of the air stream, thereby allowing for a much larger area for the user to fly. A third set of baffles is located just below the safety netting and is the final straightener for the air stream, and, provides a final safety grid for the user. Another very important aspect of the inventors design, is the safety netting which keeps the user of the unit from falling onto the metal grid air stream re-director, above the propeller. The prior arts teach a system of netting, not unlike a trampoline top which is supported by elastic strands, or, springs, located at strategic places around the peripheral of the netting. The inventor of the freefall simulator has changed this design to a system of webbing cords, designed to form a complete net over the final grid, each of the crossing cords being attached to the frame of the netting. Therefore, if, by chance, one of the cords breaks, only that little section of the netting will lose its support, and eliminates the possibility of the user falling through the opening created, as is possible in the case of the prior arts studied. In addition to this safety netting, the inventor has added a multi density, layered landing cushion device which incorporates a beveled, or, tapered edge at the peripheral of the safety netting, or, air stream, to eliminate the cause of some serious accidents, when, as in the prior arts, the user inadvertently is ejected from the air stream, and finds themselves partially in, and partially out of the air stream. The multi density, layered cushion adapts to the varying weights of the users, and the tapered edge of the cushion immediately surrounding the air stream allows the users body to land at a safe angle, rather than landing on an edge of a cushion. Further, the inventor has found that when a user is inadvertently ejected from the air stream, and lands on the cushions depicted in the prior arts, there is a possibility of an arm, or leg, being caught between the individual cushions, with the resulting serious accident. The inventor has eliminated the possibility of this sort of accident by eliminating the individual cushions, and providing a continuous covering over the cushions, with "no separations", which eliminates the possibility of an arm, or leg, being caught in the separations. One final safety hazard, as taught in the prior arts studied, and, experienced by the inventor, is the possibility of the novice flyer to be thrown upwards, or, sidewards, ending up "out of control", and being tossed out of, or, thrown too far upwards, with the resulting cause of a major accident The inventor has eliminated this prob]em by installing a three point harness, which can be worn by the novice, or, the experienced flyer, if desired. This three point harness restricts the movement of the flyer to the extent that they are always held in the air stream. The extent of travel of the harness is adjustable, and therefore is not so restrictive to keep the flyer from experiencing the full extent of the free fall sensation, while still using the safety harness. A final problem with the machines taught in the prior arts is the noise pollution problem, which is introduced by the use of a gear driven transmission system. This noise pollution is of major proportions, due to the use of a large diesel engine, powering a large diameter aircraft propeller, via a system of gear reduction devices, and a drive shaft transmission device. All of these units, working in conjunction, tend to create a noise pollution situation, which is definitely excessive, if not intolerable to the neighbors. The inventor has overcome most of these noise problems via the introduction of a hydraulic drive system, however, additional devices have been invented, to further decrease this noise pollution problem of the freefall simulators of the prior arts. First, a high "berm" noise directing earth pile, completely surrounds the freefall simulator, directing any noise which escapes the building itself, to an upward direction. Second, the understructure of the deck above the propeller is protected with a system consisting of an acoustic blanket of sound proof panels, which absorbs the sound produced inside the freeflight unit itself, rather than allowing them to reach the peripheral of the building.
Third, a system of suspended baffles surround the entire air stream, and peripheral of the unit, to absorb most of the sound waves reaching them, and lastly, a shroud around the peripheral of the propeller itself, consisting of a perforated inner shield, which directs any deflected sound waves to the absorbing acoustical blanket, and allowing the remainder of the sound waves to pass through the perforations, into the center of the unit, which is filled with a sound absorbing batting material. The inventor feels that he has designed a freefall simulator, which is a much improved, much safer, and much more efficient unit, than is taught in the prior arts.